Vehicle seat backs and related cushions are made from numerous materials. They are configured in various shapes and sizes to accommodate the specific requirements of a customer or vehicle in which they are deployed. One material installed in passenger and commercial vehicles is real or synthetic leather. Seat cushions may include a top surface of leather and an underlayment of a stiff backing material attached to the backside of the leather, with foam padding inserted between the top surface and the underlayment.
Although the stiff backing material may facilitate manufacturing and assembly processes, using such a material on a vehicle seat back has certain drawbacks. For example, the stiff backing material has different stretch characteristics from the leather upper material. This can lead to crease lines in the resulting seat back cushion surface.
One concern is that many seat backs use a thick seat trim cover panel made of multiple layers—e.g., an upper material, a foam wadding material, and a backing material. Such a seat back may not lie flat when attached to a seat frame. The process of attaching the backing material to the leather material with a foam padding interposed may result in a seat back cushion having a rear surface that undulates.
Another reason that a seat back cushion may be difficult to attach to a seat structure is that many cushions for example are manufactured with a generally rectangular perimeter. This facilitates the manufacturing processes by presenting material pieces that can readily be cut and assembled. For instance, if the entire seat cushion has a generally rectangular perimeter, the piece or pieces of foam padding can also have a generally rectangular shape. This makes it easier to insert the foam padding into pre-sewn pockets formed by the leather and the stiff backing material. Despite the ease of manufacturing, a rectangular shape may be suboptimal from a fit and finish perspective.
It would therefore be desirable to provide a method of manufacturing a seat back cushion and assembly that overcome some or all of these problems.
Among the art considered in preparing this patent application are U.S. Pat. Nos. 3,222,697; 4,754,720; 7,823,980; 8,584,333; 8,967,712; 2013/0140867; WO 2012/028218; DE 10 2010 035 845; EP 2 611 653; FR 1 456 564; and GB 2439922.